Tjoe, I think I got a shadow effect in that photo. Mine is actually very similar to yours in color. I hadn't noticed those ridges before seeing the photo though. No idea what that's about...do you?
Re the altitude: Our summer sun is crazy intense with humidity in single digits. Many plants labeled "full sun" for regular sea level areas will fry here in May through July so I have to acclimate plants slowly and carefully to determine if they can take it. I had this pot in morning and late afternoon sun but shaded mid-day until it went into mostly shade a month or so ago. This photo was taken in June and you can see the color stress on the...one in the front whose name I can't recall.
I might try a separate pot and more sun next summer to see if I can entice it to flower.
